JPH0334515Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a piston ring for a piston of an oil-free reciprocating compressor, and more specifically, to a piston that prevents gas from leaking from a notch in the piston ring. It concerns the structure of the ring.

(b) Prior art There is a fourth groove between the inner surface of the cylinder of an oil-free reciprocating compressor and the outer diameter of the piston to prevent seizure.
As shown in the figure, it is necessary to provide an interval d of approximately 1 mm. The piston ring 2 that fits into the piston 1 is divided into three parts by cutting out one part of the ring as shown in Fig. 3a, or cutting the ring at three places as shown in Fig. 3b. A piston ring is used. A piston ring made of an elastic material such as fluororesin is cut out at one point, and a piston ring made of a hard material such as carbon is divided into three parts. Fig. 4 is an enlarged sectional view of the part of the conventional piston where the piston ring is fitted, and 2 is one or three places.
The piston ring is notched at two places, and the tension ring 3 fitted inside the piston ring biases the piston ring in the direction of expanding its diameter.
It slides in close contact with the inner surface of the cylinder 4.

(c) Problems to be solved by the invention In the piston of the conventional oil-free reciprocating compressor mentioned above, as shown in the AA cross-sectional view of FIG. Gas leaks through 〓6, reducing the efficiency of the compressor. Cross-sectional area S of the part where the gas leaks
The space between the piston and cylinder is d, the width of the notch is W, and the gap is S=d×W, and the amount of gas leakage is considered to be proportional to this cross-sectional area.

Since the piston ring 2 is urged in the direction of expanding its diameter by the tension ring 3, the piston ring gradually expands as the piston ring 2 wears. As a result, the width W of the notch 5 gradually increases, and the gas leakage cross-sectional area S further increases, resulting in a further increase in the amount of gas leakage.

Therefore, an object of the present invention is to provide a piston ring with less gas leakage in an oil-free compressor.

In view of the above-mentioned problems with the piston ring of the conventional oil-free compressor, the present inventor proposed a piston ring for the oil-free reciprocating compressor in existing application No. 60-111541 as shown in FIG. A cut piston ring 7 with a notch in one or more places is placed on the high pressure side of the compressor, and an annular endless piston ring 8 with no notches whose outside diameter is approximately equal to the cylinder inside diameter is placed on the low pressure side of both piston rings. It has been disclosed that these are used by stacking them on top of each other. In the piston ring mechanism shown in FIG. 5, the cut piston ring 7 is urged from the inside in the direction of expanding its diameter by the annular tension ring 3, as shown in FIG.
Further, fluid pressure from the high pressure side is applied to the inside of the cut piston ring 7 through the gap 6, and strongly presses the cut piston ring 7 outward.

As a result, the sliding friction force between the inner surface of the cylinder 4 and the cut piston ring 7 increases, causing a problem that the cut piston ring 7 wears out prematurely.

(d) Means for solving the problem As a result of repeated research by the present inventor in order to solve the above problem, a cut piston ring with a notch was replaced with an annular endless piston ring without a notch on the low pressure side. They discovered that by placing both piston rings on the high-pressure side and using them one on top of the other, fluid pressure from the high-pressure side is prevented from being applied to the inside of the cut piston ring, and wear on the piston rings can be reduced. It has arrived.

That is, the present invention provides an oil-free reciprocating compressor in which a cut piston ring with one or more notches is cut on the low pressure side of the compressor so that the outer diameter is approximately equal to the cylinder inner diameter. The gist of the present invention is to provide a piston ring characterized in that an annular endless piston ring without a notch is placed on the high-pressure side, both piston rings are stacked on top of each other, and the piston rings are fitted into a piston ring fitting groove of a piston.

Next, the content of the present invention will be explained in detail with reference to the drawings. Fig. 1 is a partial sectional view of a piston fitted with the piston ring of the present invention, Fig. 7 is a BB sectional view of the same,
FIG. 8 is a CC sectional view of the same, and FIG. 9 is a partially enlarged sectional view of FIG. 1. In the drawing, 7 is a cut piston ring with one or three notches,
Tension ring 3 consisting of an annular spring inside
is biased in the direction of expanding the diameter. 8 is an annular endless piston ring without notches, and the cut piston ring 7 and the endless piston ring 8 are placed one on top of the other so that the endless piston ring 8 is on the high pressure side, and the distance ring 10 is placed on the piston 1. It is attached to the formed piston ring fitting groove 9.

Reference numeral 11 denotes an O-ring groove provided on the side surface of the piston ring fitting groove 9 facing the endless piston ring 8, and the O-ring 12 fitted in the O-ring groove 11 creates a gap between the side surface of the piston ring fitting groove 9 and the endless piston ring. can be completely sealed.

However, the thickness of the distance ring 10, that is,
The width of the piston ring fitting groove 9 is made to be almost equal to the thickness of the cut piston ring 7 and the endless piston ring 8, and the distance between the piston rings 7, 8 and the side surface of the piston ring fitting groove 9 is If it is kept extremely small, the O-ring 12 is not necessarily necessary. The cut piston ring 7 is made of a material commonly used for oil-free piston rings, such as fluororesin such as polytetrafluoroethylene, epoxy resin containing carbon fiber, polyimide resin, or carbon. In the case of a hard material such as carbon, the cut piston ring 7 is divided into three parts by notching at three places, and in the case of a soft material such as fluorine resin, one is used.
A cut piston ring 7 in which only a portion is notched is used. The endless piston ring 8 is made of a self-lubricating material with a small coefficient of thermal expansion.
For example, epoxy resin or carbon reinforced with carbon fiber is used. The outer diameter of the endless piston ring 8 is manufactured so that the distance between it and the inner surface of the cylinder is as small as possible.

FIG. 10 shows another embodiment of the cut piston ring 7 and the endless piston ring 8 of the piston ring mechanism of the present invention. Here, an annular step 13 is provided on the inside of the endless piston ring 8, and an annular step 14 is provided on the outside of the cut piston ring 7. They are separated and fitted into each other.

(e) Effect When the piston ring of the present invention is attached to the piston of a reciprocating compressor, when the piston is operated, the endless piston ring 8 is caused by the pressure of the gas on the high pressure side.
The piston rings 7 having the and notch portions are brought into close contact with each other and pressed against one side of the piston ring fitting groove 9,
The cut piston ring 7 slides while being pressed against the inner surface of the cylinder 4 by the tension ring 3. Since the endless piston ring 8 has only a small gap between it and the inner surface of the cylinder 4,
As shown in FIG. 7, most of the area between the notches 5 of the piston ring 7 is the endless piston ring 8
The amount of high-pressure gas leaking through the notch 5 of the piston ring 7 is significantly reduced.

Since the endless piston ring 8 blocks high-pressure fluid pressure from being applied to the inside of the cut piston ring 7, the cut piston ring 7 is not strongly pressed against the inner surface of the cylinder 4 due to the high fluid pressure, and the cut piston ring 7 is prevented from being strongly pressed against the inner surface of the cylinder 4. There is less wear on the piston ring 7.

Furthermore, the endless piston ring 8 has a slight space between it and the inner surface of the cylinder 4, so that it is not strongly pressed against the inner surface of the cylinder when sliding. Therefore, the wear of the endless piston ring 8 is small, and the distance between it and the inner surface of the cylinder 4 is always maintained at a very small distance.

Further, by providing an O-ring 12 between the endless piston ring 8 and the piston ring fitting groove 9, it is possible to completely prevent high-pressure side fluid pressure from being applied to the inside of the cut piston ring 7.

As shown in FIG. 10, annular steps 13 and 14 are provided on the inside of the endless piston ring 8 and on the outside of the cut piston ring 7, respectively, and when they fit together, the cut piston ring 7 becomes the inner tension ring. 3, it is urged in the direction of diameter expansion,
When the outer peripheral surface of the cut piston ring 7 gradually wears out due to sliding on the inner surface of the cylinder 4, the stepped portion 13,
14, when the cylindrical surfaces of the stepped portions 13 and 14 come into contact with each other, the cut piston ring 7 cannot expand any further, so that the wear of the cut piston ring 7 stops. If the cut piston ring 7 and the endless piston ring 8 are not provided with the steps 13 and 14, if the cut piston ring 7 continues to wear out, the tension ring 3 will eventually slide directly onto the inner surface of the cylinder 4. This will cause significant damage to the inner surface of the cylinder 4.

Even if the wear of the cut piston ring 7 is accelerated for some reason, the stepped portions 13 and 14 shown in FIG. Piston rings can be used.

(f) Effects of the invention If the piston ring mechanism of the invention is used as a piston ring for an oil-free reciprocating compressor, leakage of gas on the high pressure side will be reduced and the efficiency of the compressor will be improved.

The cut piston ring is not strongly pressed against the inner surface of the piston, so there is less wear, and the life of the piston ring can be extended. Furthermore, even if a piston ring with notches wears out and the gap between the notches becomes large, the amount of high-pressure gas leaking through the gap can be kept to a minimum, extending the life of the piston ring. can.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an example of a piston equipped with the piston ring mechanism of the present invention, FIG. 2 is a sectional view of a piston equipped with a conventional piston ring, FIG. 3 is a plan view of a conventional piston ring, and FIG. The figure is a partially enlarged cross-sectional view of a piston equipped with a conventional piston ring, and FIG. 5 is a cross-sectional view of a piston equipped with the piston ring mechanism of the prior application. Figure 6 is a cross-sectional view of AA in Figure 2, Figure 7 is a cross-sectional view of BB in Figures 1 and 5, Figure 8 is a cross-sectional view of CC in Figures 1 and 5, and Figure 9 is a cross-sectional view of CC in Figures 1 and 5. It is a partially enlarged sectional view in the figure. FIG. 10 is a sectional view of another embodiment of the piston ring mechanism of the present invention. 1... Piston, 2... Piston ring, 3... Tension ring, 4... Cylinder, 5... Notch, 6
... Between, 7... Cut piston ring, 8... Endless piston ring, 9... Piston ring fitting groove, 10... Distance ring, 11... O-ring groove, 12... O-ring, 13, 14... Step part, 15...
Between.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In an oil-free reciprocating compressor, a cut piston ring whose ring is notched at one or more places on the low-pressure side, and whose outer diameter is approximately equal to the inner diameter of the cylinder. A piston ring machine groove characterized in that an annular endless piston ring without a section is arranged on a high pressure side, both piston rings are overlapped with each other, and the two piston rings are fitted into a piston ring fitting groove of a piston. (2) The piston ring mechanism according to claim 1, wherein an O-ring is provided between the endless piston ring and the side surface of the piston ring fitting groove facing the endless piston ring for sealing. (3) A utility model according to claim 1, wherein an annular stepped portion is provided on the outer periphery of the cut piston ring and on the inner periphery of the endless piston ring, respectively, and that fit into each other with an annular gap. Piston ring mechanism.